Why Does Hair Turn Grey?

We explain what's keeping the hair dye industry in business.

Graying hair is one of the most common and inevitable signs of aging we experience—yet it’s also one of the most mysterious. We all know someone who started graying in her early 20s while others don’t go gray until their 60s or later. So, why does hair turn gray — or even white sometimes? And why does it happen for some people sooner than others?

Well, to start, stress isn’t a factor. I know—mind blown. According to WebMD, various studies have found that, contrary to popular belief, extreme stress won’t cause your hair to go gray prematurely. And though there’s not much definitive proof of what does cause hair to turn gray, there are a few commonly believed reasons:

  • Melanin Production: The pigment in hair is called melanin, and it’s produced by cells in the hair bulb. As we age, the cells stop producing that pigment, causing our hair to grown in gray (with minimal melanin) and white (with no melanin), according to ScientificAmerican.com.
  • Genetics: Many studies have shown that the time and extent of melanin decrease in hair is linked to genetics, and people are predisposed to go gray at or around a certain age. Also, in general, according to a WebMD, Caucasians start graying in their mid-30s, Asians in their late 30s, and African-Americans and Africans in their mid-40s. And, per a study published in the International Journal of Trichology (which focuses on the scalp and hair), graying is considered to be premature if it happens before age 20 in white people, 25 in Asian people, and 30 in African people.
  • Hydrogen Peroxide Build-Up: No, we’re not referring to the hydrogen peroxide that comes in a bottle:  Hair cells actually make small amounts of hydrogen peroxide themselves. But over time, those amounts build up and according to a study published in The FASEB Journal that may result in the growth of gray hair. Hydrogen peroxide buildup blocks the normal synthesis of melanin, thereby essentially bleaching your hair from the start. Another factor in this process is catalase, an enzyme produced by our bodies that breaks down hydrogen peroxide. But, with time, we produce less of the enzyme, which means there’s less of it to break down the hydrogen peroxide.
  • Environmental Factors: According to the study published in the International Journal of Trichology, many studies have also found a link between various environmental factors and graying hair. Things like ultra-violet light exposure, nutritional deficiencies (primarily vitamin D3 and B vitamins), and even smoking can lead to premature loss of pigment in your hair. Yet another reason to quit smoking and eat your vitamins!

READ MORE: Expert Tips for Dyeing Your Hair Gray — On Purpose


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  • cal3301

    This article is BS. I have been taking vitamins B complex and D3 for over half my life for sport related injuries. I had my first gray hair at 26 at the crown of my head. Red heads do get gray hair also.(Many redheads are out of a bottle). My strawberry blonde hairs at the front of my face went white in my 30’s. The rest started graying in my 40’s. I stopped trying to dye them in my 50’s and actually like how they came in. More and more people are accepting the gray color and should never, ever, be ashamed of them. All the vitamins in the world, won’t stop it from happening or slow it down.

  • willy`nilly

    ~My first white hairs, all three of them, showed up when I was aged 13. By the time I was 30, my head was probably 75% pure white, not grey. At age 40, my family was calling me “cotton top,” and a kindly man said my hair was a “beautiful platinum silver!” Only once did I dye my hair, at my mother’s insistence, when I was about 23, because she said MY hair made HER look old! After that first dye job wore off, I never looked back and have proudly worn my crown of bright, white hair all these years!` My original hair color was a deep auburn, and for many years after my initial “turning,” I had a deep red streak that could be seen only when my hair was lifted from the nape of my neck.

  • jsmoot

    I dieted hard and in an unhealthy way for many months at age 42 and I got my first few gray hairs plus an erratic period. Could be a coincidence; you’ll have to form your own conclusions. I went back to a “rest” period of non-dieting and (warning: TMI) increased sexual activity as my strategy and I can say at least my period has gone back to normal. I haven’t seemed to get any more gray hairs, but that is a harder thing to judge objectively. I would like to add that both the negative effects and the positive effects took months to come to pass.

    My personal theory is that while we can’t change age or genetics, which I think play a large role, we can change our nutrition and other factors that might influence our youthfulness, such as sexual activity (which is a primary biological factor, in my opinion). I wouldn’t be surprised if the best anti-ageing elements in life that we can control are weight-lifting and sex, so those two things are part of my main plan.

  • Dania Dania

    How can you possibly say stress is not a factor? There is much information on how increased cortisol (the hormone your body produces when under stress) directly impacts your body’s absorption of nutrients and how it utilizes those that it does absorb. One only needs to look at every US president in history to see how stress not only whitens and/or greys hair but also how it accelerates other outward signs of aging. ~Dania Drewing, author of “Vanity Nutrition: Using Food, Not the Scalpel”

  • Andrea Smith

    I will be 71 this month, and my hair is still not real grey. I think that genetics is a real factor. If your body uses B vitamins effectively, then I think that is one reason that some people do not grey as early as others. Of course our diet, has a lot to do with it too. I don’t smoke or drink alcoholic beverages and very little soft drinks, and I try to eat a well balanced diet. I have had a lot of stress in my life, and that was not a factor for me. I do know of a woman that had a massive heart attack and seemed to grey overnight after that happened. I guess I am one of the lucky ones.

  • Linda Friedlander

    Where can we get a sample to test before buying a $90 bottle of shampoo?